pityriasis

pityriasis /pit·y·ri·a·sis/ (pit″ĭ-ri´ah-sis) any of various skin diseases characterized by the formation of fine, branny scales.

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pityriasis al´ba  a chronic condition with patchy scaling and hypopigmentation of the skin of the face.

pityriasis ro´sea  a dermatosis marked by scaling, pink, oval macules arranged with the long axes parallel to the cleavage lines of the skin.

pityriasis ru´bra pila´ris  a chronic inflammatory skin disease marked by pink scaling macules and horny follicular papules, beginning usually with seborrhea of the scalp and face, with keratoderma of palms and soles.

pityriasis versi´color  tinea versicolor.

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pit·y·ri·a·sis (pt-r-ss)

n. pl. pit·y·ri·a·ses (-sz)

Any of various skin diseases of humans and animals, characterized by epidermal shedding of flaky scales.

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pity·ria·sic (-sk) adj.

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pityriasis

[pitərī′əsis]

Etymology: Gk, pityron, bran

any of a number of skin diseases that have in common lesions that resemble dandrufflike scales without obvious signs of inflammation.

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pityriasis [pit″ĭ-ri´ah-sis]

any of various skin diseases characterized by the formation of fine, branny scales.

acute lichenoid pityriasis an acute or subacute, sometimes relapsing, widespread macular, papular, or vesicular eruption that tends to crusting, necrosis, and hemorrhage; when it heals it leaves pigmented depressed scars, followed by a new crop of lesions. Progression to the chronic lichenoid form occasionally occurs.

pityriasis al´ba a chronic condition with patchy scaling and hypopigmentation of the skin of the face.

chronic lichenoid pityriasis a chronic brown to red-brown scaly macular eruption, seen mainly on the trunk, with epidermal changes and a perivascular lymphocytic infiltrate. It may arise independently or happen as a progression of the acute lichenoid form.

pityriasis ro´sea a common acute or subacute, self-limited exanthematous disease of unknown etiology. It begins with a solitary red to tan plaque (herald plaque), usually on the trunk, arms, or thighs, which is followed by similar but smaller papular or macular lesions; these later may peel and leave a scaly collarette.

pityriasis ru´bra pila´ris a chronic inflammatory skin disease marked by pink scaling macules and cone-shaped horny follicular papules; it usually begins with severe seborrhea of the scalp and face, associated with keratoderma of palms and soles.

pityriasis versi´color tinea versicolor.

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pityriasis

a group of skin diseases in humans characterized by branlike scales on the skin surface. The skin is not thickened and its surface is unbroken. Pityriasis rosea of pigs is the only diseases in animals that is similar.

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pityriasis rosea

a disease of pigs, most commonly white breeds such as Landrace, up to 3 months old characterized by circular lesions 1 inch (2-3 cm) diameter which often coalesce to produce large irregular lesions. The central area of the lesion is an area of comparatively normal skin, covered by thin brown scales and surrounded by a very narrow, 1 to 2 mm raised zone of erythema. There is no irritation or no bristle loss and spontaneous recovery is usual. The etiology is unknown. Called also porcine juvenile pustular psoriasiform dermatitis, pseudoringworm.